Where elongated work stock is to be controllably fed to an automatic machine tool, it is common to provide a feed apparatus operable to engage the stock at one end of a guide tube and urge it longitudinally toward and out the other end at a controlled rate to within the work station of the machine tool. In the case of elongated bar stock being fed to an automatic lathe, it is known to utilize an elongated tubular support cylinder in which to receive the bar stock. A displaceable piston within the tube is hydraulically actuated and is located at one end of the tube for advancing the bar stock out the other end into the work station of the lathe. To minimize bar stock vibration during its support within the tube, it is known to supply controlled quantities of hydraulic fluid to within the tube in order to surround the rotating bar and provide cushioning against vibration. Typical apparatus of the foregoing type is disclosed, by the way of example, in U.S. Pat. No. 4,507,992 and U.S. Pat. No. Re. 29,905.